Electrical lightning arrester



Sept 16 1952* G. RYDBECK 2,611,108

ELECTRICAL LIGHTNING ARRESTER Filed Sept. 25, 1947 Patented Sept. 16,1952 UNITED STATES PATENT OFFICE ELECTRICAL LIGHTNING ARREs'rERGstaRydbeck, Vasteras,v Sweden, assgnor to Allmanna Svenska Elektriska.Aktiebolaget, Vasteras, Sweden,` a Swedish corporation Applicationseptember 25, 1947, serial No. .776,100 .I InSweden September 24, 1941section 1,1 ub1ie Law 69o, August 8, 1946 1 jj Patent expires September24, 1961 6 Claims. (Cl. 315-36) In electrical lightning arresters witharc gaps 'connected in series with voltage dependent resistances, it hasbeen proposed to shunt the resistances by capacities in order todecrease the voltage drop over the resistances caused by the chargingcurrent to the arc gaps. In this way "any occurring over-voltage isdistributed practically only over the arc gaps, so that the lightningarrester will function at a lower over-voltage than if a part of theover-voltage also is consumed as a voltage drop over the resistances.

In the case when the lightning arresters consist of a plurality ofseries-connected units of arc gaps or groups of arc gaps connected inseries with resistances, it is important that all units should receiveequally large parts of the overvoltage. 'For this purpose a capacitivepotentiometer has been Kconnected in parallel to the chain of arresterunits, and the different units have then been connected withcorresponding parts of the potentiometer. It is important that thecapacities forming the capacitive potentiometer should be large incomparison to the capacity of the arc gaps and to their capacity toearth, because only in this case will the influence of the potentiometeron the voltage distribution over the arrester chain be dominant.

The carrying out of the two-above-mentioned measures requires, however,the use of several comparatively large condensers, so that the arresteraggregate will occupy a considerable volume if condensers of the usualform are used.

Thepresent invention has for its object an arrangement in'whichsuiciently large capacities can be arranged in the arrester in themanner indicated above without the volume of the arrester beingincreased to any great extent and without the height of it beinggreater, but instead the invention allows the arrester to be built verylow.

According to the invention the arc gaps and resistances are arranged inpiles side by side and in such manner that between the groups of arcgaps and between the diierent resistances insulating sheets arearranged, which also serve as condensers on the one hand for shuntingthe resistances and on the other hand for equalizing the voltagedistribution over the units in the arrester chain. Metal coatings may beapplied on the insulating sheets, so that they can at the same timeserve as connections between the arc .gaps and the resistances. It isthus suitable to make a part of the insulating sheets with their metalcoatings long so that they project in between the units of the differentpiles. As they reach from one pile to the adjacent pile,-these will beconnected with each other at the desired points.

The piles may suitably be arranged in the corners of a polygoncorresponding to the number of piles, and the whole is suitably enclosedin an insulating container, for instance in a porcelain cylinder.

In the accompanying drawing,

Figure 1 shows a form of the invention. In this the spark gaps arearranged in a pile, and the resistances in two piles arranged on theside of the arc gap pile. In the drawing the piles are drawn side byside in `spite of the fact that in reality they are arranged at the'corners ofva triangle.

Figure 2 shows diagrammatically the electrical connection of thedifferent parts of the arrester.

In the drawing, I designatesthe electrode plates of the arc gaps whichare provided withA la plurality of depressions and 2 are distance piecesinserted in these depressions between the electrode plates, whichdistance pieces are made of a suitable ceramic material containingsilicium carbide or of a mixture of synthetic resin having a high carbonblack content, with a high resistance and thus serve as voltageequalizing resistances. 3 are the voltage dependent resistances formedas cylinders of a ceramic 1resistance material such assilicium carbideand 4 and 5 are insulatingsheets of mica or porcelain inserted betweenthe resistance cylinders or between-the groups of arc gaps. Theinsulating sheets 4 are connected with each other by means ofconnections 6, whereas the insulating sheets 5, which are insertedbetween the groups of the arc gaps are so long that they reach inbetween the resistances. The insulating sheets 4 with their metalcoatings will therefore form two parallel connected capacitivepotentiometers, the parts of which are connected with the arrester chainat corresponding points, whereas the insulating sheets 5 with theirmetal coatings form capacities which shunt the resistances 3. Thedifferent capacities are designated in Figure 2 by the same index as inFigure 1. By giving the insulating sheets a suitable thickness, thecapacities of the potentiometer can be given the magnitude necessary toreach the desired distribution of the voltage.

The whole complex is enclosed in a porcelain cylinder 'I with a metalbottom 8. The cylinder 1 is closed at the upper end by a metal cover 9,and both the bottom and the cover are provided with terminals (notshown). Between the cover or the bottom and the outermost insulatingsheets, yielding washers I and Il are inserted, and the connectionbetween the cover 9 and the bottom 8 with the. beginning and the. end4of thearrester chain isperformedby means of the Vconnections I2 and I3.

The above described arrangement may of course be varied in many wayswithout departing from the invention. For instancelthe;.arc;gaps andresistances may be arranged in one or more piles. The arrangement may;also ibe Vsuch that the. capacities shunting the resistances shuntthese entirely, but it is also possible that only a part of theresistances. arefshunte'd. Eurther the capacities serving aspotentiometer maybe` pendent .resistances. series-connected groups ofarc-gaps .in series `,With-*said* resistances, `said igroups of arc gapsand voltage dependent re- -sistances being arranged in parallel columns,-fcondenser elements inserted in said columnsfam `consistingofinsulating-sheets having Inetalcoatingsonbotlr sides;providing-electricalconnection between ,thecolumns, and-Vmetalconnectingielements between said condenser elements; andsaidvgroups; of; arcl gaps.. andresistancessand connect- .ing `saidVcondenser elements in parallel with said: arc gap. -resistancefgroups3. A- lightningarresten comprising voltagede- .pendentresistances,series-connected groups of arcggaps. in series with said resistances,Lsaid -arc ,gaps `-and ,voltage dependent 4 resistanoes V:being vpiled upin parallel columns, condenserl elements Iconsistingoinsulatingsheetshavingmetal coatingson bothsides insertedin saidcolumns; metalconnecting elements :between said condenser elements and-saidgroups` of.arcvr gaps and resistences andconnectng said: condenser. elements in 4parallel with said arc gap resistance groups, and condenser membersconsisting of insulating sheets having metal coatings on both sides andbeing. inserte d in said columns and vextending 'from yone ,column toanother, the coatings of said condenser members forming connections toconnect said condenser elements in parallel with said voltage dependentresistances.

4.,A;1ightning;arrester comprising voltage dependent resistances andgroups of arc gaps dis- ;posedzin `columns arranged side by side, and

condenser elements consisting of insulating sheets having metal coatingson both sides inserted in said columns andproviding electricalconnection A'between-adjacent columns.

. 5. A lightning arrester, comprising voltage de- ,pendentresistancesand groups of arc gaps disposed in columns arranged side by side,condenser elements consisting of insulating sheets having metalcoatingszon both sides inserted in -said columns andproviding electricalconnection between :adjacent: columns, and metal4:connectionsi-seriesrconnecting, groups of said. voltageV dependentresistancesand groupsof saidizarc. .gaps in saidcolumns.

6. A lightning arrestercomprisng aplura1ity ,of parallel columns ofelements, onefoffsaidcolumns containing at leastsparkgaps and.V anothercontaining at least voltage dependent resistances,

Vmeans* connecting. elements of the columns in a series connectionwhich.includes alternately. at least one resistanceeand at least one..spark-gap at yadjacent levels in said columns, insulating membersseparating elements of said columns,

said members having on both sides layers of conducting materia1, atleast some ofisaid vmembers extending from column Vtofcoluinn andthelayers thereoniormingapart of suchseriesconnection. Y

GOSTA RYDBECK,

REFERENCES CITED The following :references are of f record; in :th le Iof :this fpatent:

Number Name 1,658,746 Steinmetz Feb. 7,; 1928 1,902,510 McEachron `Mar.2l, .1933

2,324,108 Pyk Ju1y 13, 19 4 'FOREIGNZPATENTS Number Country l Date Y Y560,306 Great Britain Ma1.` 29,1944

